I don't necessarily have a ton to say about this game, because it was a little short and has very little plot to speak of, but of what I have to say, it's all great. I love this game. It's a little easy, but not very easy. I understand this is mostly because it's not designed to be hard. It's kind of hard to help promote Cat and her music if noone can reach the end of the game.
You have successfully combined my favorite game series of yours with a wonderful set of music that changes the feel of the game. I like this aspect. Daymare itself has a very cold and dreary feel to it, shown easily by a lack of color and the background music, but you spend the game breaking that and you end the game by escaping the town.
Overall, bravo. You've made an amazing platformer that combines Daymare with music (two of my loves) without ruining either version. It's a very well made game.